84. Uncontrolled hypertension Flashcards
A 48-year-old male patient presents for day-case inguinal hernia repair.
On arrival on the ward, his blood pressure is 220/130.
What would you do?
The patient’s blood pressure should be rechecked ensuring that the cuff size is
correct.
Ascertain whether he is usually normotensive.
A blood pressure this high is pathological and not likely to be due to anxiety
(white coat hypertension).
However, it could be rechecked following an anxiolytic if it is deemed appropriate.
It may be that he is already on anti-hypertensives, but has not taken them recently.
This blood pressure is extremely high and raises the (rare) possibility of
malignant hypertension.
Other features of this include papilloedema,
encephalopathy and end-organ damage.
If these features were present, then it would be a medical emergency and necessitate admission to hospital and urgent anti-hypertensive therapy.
On rechecking, the BP is 200/120. Will you anaesthetise this patient?
No. The surgery should be postponed until the blood pressure is under control
and an explanation given to the patient.
He needs to understand the implications of having uncontrolled hypertension both in terms of having an anaesthetic and also the long-term health risks.
A systematic review and meta-analysis of hypertensive disease and peri-operative cardiac events demonstrated a statistically but not clinically significant association.
There is little evidence suggesting that patients with
systolic pressures <180 mmHg
and diastolic pressures <110 mmHG
have an increased risk of peri-operative complications.
The situation is less clear in patients with values above the aforementioned levels.
These patients are at more risk of the complications listed below.
However, this may relate to the presence of end-organ damage
due to hypertension rather than the presenting blood pressure values.
There is no evidence that postponing surgery reduces risk.
A medical history with regard to his hypertension, particularly looking for
an underlying medical cause (found in less than 10% of cases)
and symptoms of target organ damage should be taken.
The condition should be investigated and treatment commenced.
This would need to be co-ordinated
through his primary care physician.
Routine investigation of hypertensive patients:
Urine strip test for blood and protein
Blood electrolytes and creatinine
Blood glucose – preferably fasted
Serum Total:HDL cholesterol ratio
12-lead ECG.
(British Hypertensive Society guidelines)
What are the problems of anaesthetising a patient with uncontrolled
hypertension?
Cardiac ischaemic events (especially if LVH present on ECG)
Arrhythmias
Cerebral autoregulation reset (shifted to the right)
Exaggerated cardiovascular responses
Poor left ventricular relaxation (diastolic dysfunction)
Renal failure
Bleeding
How soon do you think you would be happy to anaesthetise this
patient?
Treatment needs to be established and continued for several weeks
with thorough pre-operative evaluation of end-organ damage.
The numbers may ‘normalise’ quickly, but several weeks of therapy are needed to reduce the abnormal vessel reactivity.
The patient could then be anaesthetised when the
diastolic pressure is controlled at or below 90 – 110 mmHg and maintained
within 20% of pre-operative levels during surgery.
The treatment target BP should be <140 mmHg systolic and <85 mmHg diastolic in non-diabetics.
Which anti-hypertensive medication would you prescribe?
For each major class of anti-hypertensive drug, compelling indications and
contraindications exist for use in specific groups of patients.
First-line treatment in this patient would be an ACE inhibitor,
probably with the
addition of a calcium channel blocker.
Anti-hypertensive therapy recommendations
Agent Compelling indication
a-blocker
Prostatism
ACE-Inhibitor
Heart-failure, LV dysfunction
Type-1 diabetic nephropathy
Angiotensin II antag.
Intolerance to ACE-I
Hypertension with LVF
β-blocker
MI, angina
Ca2+ antagonist (dihydropyridine)
Isolated systolic HT in elderly pts
Ca2+ antagonist (rate-limiting)
Angina
Thiazide
Elderly patients, secondary stroke prevention
British Hypertension Society and NICE Guidelines – which drugs?
Aged 55 and over, or Black patients of any age:
Calcium channel blocker or a thiazide-type diuretic
(Black patients are those of African or Caribbean descent,
and not mixed race, Asian or Chinese patients.)
Younger than 55:
ACE inhibitor or an angiotensin receptor blocker (if ACE inhibitor not tolerated).
If a second drug is required:
If initial therapy was with a calcium channel blocker or thiazide-type
diuretic, add an ACE inhibitor (or an angiotensin receptor blocker if
ACE inhibitor not tolerated).
If initial therapy was with an ACE inhibitor, add a calcium channel
blocker or a thiazide-type diuretic.
If a third drug is required:
If a third drug is required:
Combination of ACE inhibitor (or an angiotensin receptor blocker if an
ACE inhibitor is not tolerated), calcium channel blocker and
thiazide-type diuretic should be used.
